Process of extracting metals from their ores.



To all whom it may concern:

UNITED sTAT s PATENT OFFICE.

"WILLI AM E. GREENAWAL T, OF DENVER,' GOLOR ADO.

PROCESS OF EXTRACT ING METALS FROM THEIR ORESA Be it known that I, VVILLIAM E. GREENA- WALT, a citizen of the United States, residing at Denver, in thecounty of Denver and State of Colorado, have invented certain new and useful Improvements in Processes of Extracting Metals from Their Ores, of which the following is a specification.

I My invention relates to improvements in processes of extracting metals from their I ores.

its ores have not met with the success thatmight be expected, owing largely to the high cost of acid for the solvent, and iron for the precipitant, which are the materials ordinarily used. Electrolytic precipitation, if the acid is regenerated, is an im 'irovement; but since all ores consume much more acid than that combining with the copper, and since the regeneration of the acid is limited to that so combined, the necessity of supplying acid still exists.

Copper ores almost always contain variable quantities of gold and silver, and these metals cannot be recovered by any of the wet methods now in use. One, and sometimes two additional treatments are necessary to extract the gold and silver. The difiiculty with acid processes has been, that the acid is usually'too expensive to admit of extended use in mining districts, which are ordinarily located far from the source of acid supply. Installation of acid plants at the mines has not solved the difiiculty; It takes approximately 1.5 pounds of sulfuric acid to dissolve one pound of copper. If hydrochloric acid is used, it takes 0.6 pounds of acid to extract one pound of copper as cuprous, and 1.1 pounds as cupric chlorid. Much of the acid, whether sulfuric or hydro- -chloric, combines with the base elements in the ore and serves no useful purpose. The solution, as drawn from, the ore, is usually Specification of Letters Patent.

.No Drawing. Application filed January 16, 1906, Serial No. 296,402.

Patented Aug. 30, 1910. Renewed January 29, 1910. Serial acid; it is necessary therefore, to neutralize the free acid before precipitating the copper, iron is used as the precipitant. If this precaution is not taken the solution will neutralize itself at the expense of the iron. It is evident, that the acid, which was pr vided at some expense, must be again neutralized. at further expense, without having extracted any copper. The amount of acid which it is nccessarvto provide, is considerably more than that combining with the copper, and all the acid is irrecoverably lost. In some methods of extraction, the solution is reused after the copper has been precipitated by the iron, but these solutions are too slow in solvent action to admit of wide ap plication. r

Theoretically, 88.8 pounds of iron are required to precipitate 100 pounds of copper from sulfate solutions: In practice it takes from 200 to 300 pounds. Here again a large expense is incurred in providing iron to precipitate the copper. In commercial centers, 1

where scrap iron is cheap, this item is serious enough; but in mining districts it is fatal to the cheaprecovery of the copper. The copper precipitated by scrap iron is about 65% purity.

In my electrolytic process to be described, the copper is dissolved by dilute acid solutions, and then precipitated by electrolysis, while at the same time the acid, which was combined with the copper, is multiplied and regenerated as free acid, largely at the expense of sulfur dioxid and water. The regenerated acid solution is returned to the ore until the copper is sufficiently extracted. Sulfur dioxid, usually derived from roasting sulfid ore, is the active chemical consumed.

In working the process, the ore is first crushed to about 12 mesh. Sulfids are roasted, but the carbonates, oxide and silicates, may be treated without roasting. The ore is then placed in leaching vats for chemical treatment. Thefirst step inthe chemical treatment consists in combining 1 12i; t'fim base v fishes hydro mm: ask mm, with the supper, again Iwmulting in. this 01" "my cu'm ic chiafr-ifl.

one 131 a N1 Am 111%.2011

hie" B I (VAR. 2

t'wiua fr z m i u. Q on $5 calcium cembm chlnmd; but 3 emu-mm 0111 2:16. "W112 at once with t e QU'iJPEK. sulfate in 501w "1 22nd can'vars ix; into the cupl'ic vahlorid:

quantities of acid. A :16 in this my "1 ne-Emmi 1E Wei-y mnlemfl'e of cupric chlnriol rammed is @upmus; c1 rid Fm? pom'sd Ufwmpper from the cupric to the mmmus cemGLit-ion,

If there is gold in the ore, the acid chlorid solution is charged with chlorin, generated from salt in the electrolytic cells. This chlorin is not lost, but is ultimately converted into base metal chlorid, in which form it is again used in the solution to extract the copper and silver from new charges of ore. Theoretically, none of the chlorin, whether free or combined, is lost. It simply changes its condition from acid to chlorid in the leaching vats and is again regenerated back to acid in the precipitating cells. In practice, it is well to allow one fourth pound of salt for every pound of'copper produced.

The copper in the solution issuing from the leaching vats, will ordinarily be in the form ofcupric chlorid; a. small amount may be present as cuprous chlorid. The sulfate of copper which may be formed by the sulfuric acid, resulting from the regeneration, will he converted into the chlorid before issuing from the vats. llt is desirable to have the copper in the form of chlorid before applying the sulfur dioxid The sulfur.

dioxid is then applied to the solution to reduce the cupric to the cuprous chlorid. This is preferably done by subdividing the solution, as in ascrubbingtower, while passing the gas through it. There should also be a large excess of sulfur dioxid in the solution, to combine with the chlorin liberated during electrolysis, while precipitating the copper, as set forth in equations (8) and The excess of sulfur dioxid, not only prevents the escape of chlorin, but also overcomes the tendency of the chlorin to reconvert some of the cuprous chlorid into the c-upric chlorid. Should there be an excess of sulfur dioxid, after the solution has passed through the precipitating cells, it is again subdivided and brought into contact. with chlorin to convert. the excess into acid (according to equation 1) before again entering the leaching vat.

.lf there is silver in the ore, the solution containing cupric chlorid, is heated to convert the silver into the chlorid, and to more readily bring the chlorid of silver into solu-.

tion. Hot salt Water is a reasonably good solvent of silver chlorid, but a very impractical solvent for chlorin;

If the ore contains gold, the last charge of solution to be passed through the ore is cooled, subdivided, and as much chlorin as possible forced into it, so that the amount retained will be aslargc as possible. Chlorin is sparingly soluble in cold water, and much less soluble in warm water or in a solution of sodium chlorid. In order to'get a strong solution of chlorin, I prefer using the methods set forth in my applications for Patent Serial hlumber 47,975 tiled Feb. 19,1901; Serial Number 14%,363 filed Feb. 21, 1903; Serial Number 191,600 filed Feb. 1, 1904, which consist in general, of generating the bing tower.

siderable quantities.

chlorin from common suit by electrolysis, and bringing it incontaet with the solution while in a state of subdivision, as in a scrub- The regenerated solution contains other solvents of copper besides the acids. Among these may be mentioned ferric chlorid which will be found in the solution in considerable quantities. The ferric chlorid not only acts as a solvent for the copper, but also as an ellicient chloridizer of the silver. The ferric clhlorid also acts 'as an acid generator, t ius The ferrous chlorid is reconvert-ed into the ferric chlorid in the precipitating tanks or in the chlorin tower. When the ore contains considerable gold and silver, and not much copper, this fact taken advantage of,

by not having an excess of sulfur dioxid in the solution before precipitating and letting the chlorin, released in precipitating the copper act on the ferrous chlorid to convert it into the ferric chlorid. i

The chlorid solution is preferably composed largely of sodium chlorid. Other ehlorids will gradually accumulate in c0n- In the generation of chlorin from salt by electrolysis, caustic soda is produced at the same time. This caustic soda is added to the solvent of the copper from time to time, to purify it, by precipitating many of the base metals and regenerating sodium chlorid; thus;

The precipitated hydroxids are then filtered from the solution.

When the ore contains copper, gold and silver, it is desirable that they be ultimately recovered separately. This may be done by precipitating the gold and silver by electrolysis, with the copper, and then redepositing the copper and recovering the gold and silver from the anode slimes. Both gold and silver will be deposited either before or simultaneously with the copper in the electrodeposition, since both require a lower voltage for the decomposition of their chlorids than that required for cuprous chlorid. These metals will therefore all be deposited together on the cathode. In the electrolytic refining of the crude cathode copper, as in the case of refining blister copper, the gold and silver will remain in the anode slimes While the pure copper is precipitated on the cathode. The gold and silver may then be recovered from the anode slimes by any of the well known methods. li prefer however,

to recover the gold and silver by the method which I- will now describe. It is well known that gold and silver are readily precipitated by metallic copper, If copper is precipireadily, and separately recovered.

' chlorid iusolution; else tuted by electrolysis, and with high current density, it will. not adhere to the cathode, but fall to the bottom o'lfrthe cell as fine granular copper. Metallic copper is not reedil soluble in dilute sulfuric or hydrochloric acid, ii therefore, this gronuler precipitated copper is used to precipitate the gold and silver none of the excess of acid will be neutralized, as is the case when iron is used as the precipitant. To precipitate the gold and silver, the required 2 count of copper is precipitated with e. curl out density to give the desired fineness. Tl e copper is then placed in small tanks, rouge-d in series, one above the other, so that the solution issuing; from the leaching vets, Wili pass in turn through the copper tanks, Where the gold and silver ere precipitated, and e corresponding amount of copper going); into solution. The copper tanks are provided with suitable filters on which the copper is placed, When the copper is entiicieutly rich in gold and silver, it is finned, melted, and cost into suitable anodes, the copper precipitated on suitable cutl1odes,cnd the gold and silver recov "ed from anode slimes. lily this method of precipitating the gold and silver with the copper and then recovering the copper, with the copper in the solution obtained from the ore, the expense involved is almost negiigible factor, and the precious metals are Having thus described my invention whet I claim is;-

l. A. process of extracting copper from its ores which consists in dissolving the copper with it suitable solvent; converting the cop per in the solution, not already in the form of chlo'rid, into the chlorid by reuctine' th the chloride in. the solvent; mnvertteg ,he cupric color-1d into the ciun'ous-chlorld lry ln'iuging thesolution in contact with sulfur dioxid; maintaining suiiicient hose motel chltu'ids in the solution to retain the cuprous trolysimg the solucrate i uteri pitnte the c tion to prcc acid; and acid solution copper.

A pror ores which. i

' 55 copperlfroiu the cc er solvent into the copper and regenerate acid; endtlien f A mg the regenerated acid solution to the i r to extract more copper.

o. A process ct estl acting come-eores winch consists in ieachmg the e an acld solution of sodium chlorld sulfur dloxid to the solution to cm holding chlorin to the cuprio elilorid into the cuprous chlorid thereby forming in solution of cuprous chlorid;

vcrt the cupric chlorid into the cuprous' chlorid therehy forming a solution of cuprous chlorid; electrolyzing the cuprous chlorid solution in the presence of sulfur dicta-id to precipitate the copper and regenerate acid; and then applying the regenerated acid solution to the ore to dissolve more copper.

5. A process of extracting metals from their ores col'lteining copper, silver and gold which consists in bringing the'copper and chlorid of silver in solution by means of a suitable solvent; converting the dissolved copper into the form of cuprous chlorid; maintaining sufficient other chloride in solu tion to retain the cuprous chlorid in solutiongelectrolyzing the cuprous chlorid to precipitate the copper and regenerate acid;

solution; and then ap plying the regenerated acid solution containing ch'lorin to the ore to extract the gold.

6.. A process of extracting metals from their ores containing copper and gold which consists in treating the ore With an acid solotion containing sodium and other chloride to extract the copper; applying sulfur dioxicl to the copper solution to convert the cupric into the cuprous chloricl thereby forming e solution of cuprous chlorid; electmlyzing the cuprous chlorid solution in the presence of sulfur dioxid to precipitate the copper and regenerate acid; adding chlorin to the precipitated solution; and then applying the regenerated acid solution conehlorin to the ore to extract the A. process of extracting metals front their ores containing copper end silver use consists in bringing the copper in the me in solution by means of e suitable solvent; cin'n "erting the dissolved copper not in the form of chlorid into the chlorid; c on verting the copper chlorid into the form of 'c-uprous chlorid by the application of su1- fur dioxid; maintaining sufficient other chlorids the solution to retain the cu prone chic-rid in solution and to dissolve the siiver chiorid in the ore; electrolyzingthe cuprous chlorid in the prwence of sulfur dioxid to precipitate .the-copper and regenacid; applying chlorin to tl1e-prec1piteed solution to combine with the excess of sulfur adding chlorin to the soluacid solution containing sodium and other .chlorids to dissolve the copper and silver ing sodium chlorid; filterin chlorid; applying sulfur dioxid to the solution to convert the cupric into the cuprous chlorid thereby forming a solution of enpr'ous chlorid; electrol'yzing the cuprous chlorid solution to precipitate the copper; electrolysing salt to generate chlorin and caustic soda; adding the chlorin to the solution to dissolve thegold and other metals; and from time to time adding the caustic soda to the solution to purify it by precipitating many of the base metals as hydroxids andregenerating sodium chlorid.

9. A process of. extracting metals from their ores containing copper which consists in electrolyzing sodium chlorid to generate chlorin and caustic soda; combining the chlorin with sulfur dioxid to generate acid; treating the ore with the acid solution so formed; converting the dissolved. copper into cuprous chlorid by the application of sulfur dioxid; electrolyzing the cuprous chlorid to precipitate the copper; addingthe caustic soda to the solution from time to time to purify it by precipitating many of the base metals as hydroxids and regeneratthe solution from the precipitated hydroxide; acidifying the solution; and then again applying the acid solution to the ore to extract more metals.

10. A process of extracting copper-from its ores which consists in treating the ore with an acid solution containin sodium and ferric, chlorids; applying sul ur dioxid to the resulting copper solution to convert the 'cupric chlorid into the cuprous chlorid and the ferric into the ferrous chlorid; electrolyzing the cuprous chlorid in the pres ence of ferrous chlorid to precipitate the copper; and then applying the regenerated solution to the ore to extract more copper.

11. A processof treating-ores containing copper, silver, and gold which consists in applying an acid chlorid solution to the ore; heating the resulting cupric chlorid solution to chloridize the silver and dissolve it; applying sulfur dioxid to the solution to convert the cupric into cuprous chlorid; precipitating the copper; cooling the solution; applying chlorin to the cooled solution; and then returning the acid solution containing chlorin to the ore to extract the gold.

12. A process of extracting copper from its ores which consists in treating the ore with an acid solution containing sodium and other chlorids; filtering the solution from the ore; subdividing the solution; ap-

plying sulfur dioxid to the subdivided solution to convert the cupric chlorid into the cuprous chlorid; elcctrolyzing the cuprous chlorid to precipitate the copper and regenerate acid; and then applying the regenerated acid solution to the ore to dissolve more copper.

.13. A process of extracting copper and other metals from thcir'ores which consists in treating the ore with an acid solution containing sodium and other chlorids; filtering the solution from the ore; subdividing the solution; applying sulfur dioxid to the subdivided solution to convert the cupric chlorid into the cuprous chlorid; electrolyzing the cuprous chlorid to precipitate the copper and regenerate acid; subdividing the, regenerated acid solution; applying chlorin to the subdivided solution; and then applying the regenerated acid solution containing chlorinto the ore to dissolve more metals. v i

14. A process of extracting metals from their ores containing copper which consists in subdividing an acid solution containing sodium and other chloride; applying chlorin and sulfur dioxid to the subdivided solut-ion; treating ores of copper with the solution so formed; applying sulfur dioxid to the solution to convert the cupric chlorid into the cuprous chlorid; electrolyzing the cuprous chlorid in the presence of-sodium chlorid and sulfur dioxid to precipitate the copper and regenerate acid; and then applyand silver from their ores containing copper,

gold and silver which consists in treating the ore With'an acid solution containing sodium and other chlorids; applying sulfur dioxid to the solution to convert the cupric into the cuprous chlorid thereby forming a solution of cuprous chlorid; electrolyzing asolution containing copper with sufficient current density to give a loose deposit of nietallic copper; placing the copper in suitable receptacles; then passing the solution from the ore through the copper. to precipitate the gold and silver.

16. A process of extracting metals from their ores containing copper, silver, andgold which consists in treating the ore with an acid solution cont-ainin sodium and other chlcrids; precipitating t e copper with sufficient currentdensity to make a loose granular deposit of metallic copper placing the copper so precipitated in suitable receptacles; passing the solution from the ore through the copper to precipitate the gold and silver; applying sulfur dioxid to the solution after issuing from the gold and silver precipita-tors; and then electrolyzing] the solution to precipitate the copper.

17. A process of extracting copper from -20 v sultlng copper miuhon m convex?) v supper and. repeating r llntlj. tlm mapper 1n extractefi.

. its ores which cnnsisis 111 Leitars Paiem N0: 968,652;

is treat flier: hm

its ms, wiaich cemssi 113 minimum '50 d1S$QiV8 the copper; applying sulfur dioxid, $0 the .fsrmjng a salutiun {f5 mzpmus 0M trolyzililg the supra-us til 41101 5 6 PIGSGDGB 0i sulfm H "51 m pm. mpper and iegenemme min apply i t0 the s01 1011 "Harlem-i the a cells to comm-l;

into acid; and w ated acid soiutim:

Minn" cwweilf Kim-m 18. A process 01E wit-ham acid cfiflorid sehatiun to copxaer; applying sulfur (150.1

1m cuprm clflorid mm the supmus Chlfilw. thereby upon the application 051 W1! printed S'PBIL symbol 23598 shw'zirld Purim ma page, Hm the syrnboi 1311511 smaamw jf'nrming a :wluiinm 0,1 cupmus Qhiarid; elem trolyz ing Mm sup-runs cl hmid aoiufcion in the presazzce @f sulfa diaxifli t0 presipitate the (zop aer and. regwemta: acid; electrolyzing an; mam zhlmsid ':0' generate chkrrin mafia mlkafiijapplying the chlorin s0 W31 martian of the cbpper S0111-- waver-t 'anmlying 11m wastin- 0 tha copper salw widi 25111 precipitate 1 tha soluiiim; .ap- P regenerated acid dissolw: mare (rapper,

0% until the 3 ently mmmd.

' GlzzEENAWALTEK 1. It is hereby ceaffuifiecl that in Letters H0. 1363 6533, gmntsd .r'kug usiz 30, 19/10 4, 0f Bmwmg 'Jslomdn, for animprovw m mquiringf 525021 as fnfi-wvss: E1143 3, LHSi symhdi in .Jimuid Mimi ,8? v

' shmzfid mm Huh-5'0 and. that the said Let- L1. EHLLZFWGS,

s errors appear in $3118 Corrections in Letters Patent No. 968,652.

It is hereby certified that in Letters Patent No. 968,652, granted August 30, 1910, upon the application of Williem Greenewalt, of Denver, Colorado, for an improvement in Processes of Extracting Metals from Their Ores, errors appear in the printed speeilication requiring eorreetion, as follows: Page 2, line 3, first symbol in formula, the letters and numomlfsQ should read 80 same page, line 39, the symbol 211 0 should reed $21120; same page, lim- ,3, equation 9, should read 20H- SU +21Q0= II SO QUICK instead of A ll 50 2H SO +2HGl, and

.s'iy epage, line 122, the synlbol ()uSo, shonhl rend (Pp/@571 and that the said Letters Patent should be read with these corrections therein that the slime may conform to the record of the case in the Patent Office.

Signed and sealed this 27th day of Septem'ber, A. l)., 191).

U. C. BILLINGS,

A (rt/21g Oomwulm'rmw of Patents. 

